Question

我正在尝试根据由不同分隔符分隔的文件构建字典。例如，我通过以下方式构建文件即时读取，我需要将该行作为变量用于演示目的

g = "ENGL 1301,preprofessional,MATH 2413,"
if ","and "," in g :
    print "yay"
if "," and "," and "," in g:
    print "nay"

该文件可以有多个逗号，这意味着不同的东西，所以我试图在行中的逗号数量之间进行区分。我希望上面的程序只打印“nay”，因为字符串中有3个逗号，而不是2.我怎么能完成这个，因为上面的程序失败并打印了“yay”和“nay”

Answer 1

使用str.count：

g = "ENGL 1301,preprofessional,MATH 2413,"
commas = g.count(",")  # I put this up here so it isn't called multiple times
if commas == 2:
    print "yay"
elif commas == 3:  # I used `elif` here since `commas` cannot equal 2 and 3
    print "nay"

此外，您当前的代码不起作用，因为非空字符串在Python中评估为True。所以，这个：

if "," and "," in g :
    print "yay"
if "," and "," and "," in g:
    print "nay"

变成这样：

if True and ("," in g):
    print "yay"
if True and True and ("," in g):
    print "nay"

正如您所猜测的那样，每个if语句都将始终传递。

文件输入输出多个分隔符

1 个答案: